Selective denitrification of lipophilic pollutants from oily wastewater by peroxidation using Janus-structured amphiphilic carbon nanotubes as catalysts

Carbon nanotubes (CNTs) were tested as catalysts in the selective denitrification of 4-nitrophenol (4-NP) from oily wastewater by catalytic wet peroxide oxidation (CWPO). The CNTs were prepared by chemical vapor deposition, feeding sequentially ethylene (E) and/or acetonitrile (A) during different times until 20 min, resulting in samples E20, A20 and E10A10, the number denoting the time feeding of each precursor and the order of appearance of the letter indicating the order of each precursor. The synthesized CNTs were tested in the CWPO of 4-NP in aqueous solutions and in simulated oily wastewater (2,2,4-trimethylpentane and water) at 80 ºC, initial pH 3.5, C4-NP = 1 g L-1, CH2O2 = 3.56 g/L and Ccatalyst = 2.5 g L-1. The catalyst A20 promoted a faster decomposition of H2O2 and a lower degradation of 4-NP in the aqueous system, whereas the catalyst E20 displayed the opposite trend, since E20 was able to remove 99% of the pollutant and A20 only 69% after 8 h of reaction. E10A10 in biphasic L-L media presented the highest conversion of 4-NP after 24 h in the oily phase (51%), followed by A20 (38%) and then E20 (25%). This tendency may be ascribed to the formation of Pickering emulsions by E10A10. The amphiphilic carachteristic of this material ensures a closer contact between the liquid phases, allowing higher mass transfer.This work was financially supported by project "PLASTIC_TO_FUEL&MAT – Upcycling Waste Plastics into Fuel and Carbon Nanomaterials" (PTDC/EQU-EQU/31439/2017), Base Funding - UIDB/50020/2020 of the Associate Laboratory LSRE-LCM - funded by national funds through FCT/MCTES (PIDDAC), and CIMO (UIDB/00690/2020) through FEDER under Program PT2020. Fernanda F. Roman acknowledges the national funding by FCT, Foundation for Science and Technology, and FSE, European Social Fund, through the individual research grant SFRH/BD/143224/2019.info:eu-repo/semantics/publishedVersio

Selective oxidation of 4-nitrophenol with H2O2 in a biphasic system by janus-like carbon nanotubes

The use of petroleum-based products has increased drastically with the increase in population, resulting in the deposition of oily products in aquatic systems. It is estimated that for each ton of petroleum that undergoes refinement processes, between 0.5 and 1 ton of oily wastewaters are generated, bearing an oil concentration that may reach 40 g L-1 [1,2]. Hazardous pollutants dissolved both in oily and aqueous phases may also be found in those oily wastewaters [3], hindering their treatment through conventional processes. Furthermore, the oil phase is, in some cases, an added-value product, and its degradation results in economic losses. Thus, the development of processes that allow the removal of hazardous contaminants from oily and aqueous phases, providing an opportunity for recovering both phases, should be advantageous [3]. This work deals with the selective removal of a hazardous compound (4-nitrophenol, 4-NP) from a simulated oily wastewater (2,2,4-trimethylpentane:water = 10:90 v/v) by an oxidative process considering H2O2 as oxidant and amphiphilic Janus-like carbon nanotubes as catalysts. Amphiphilic catalysts were selected since they should present advantages in this process due to their ability to interact with both aqueous and oily compounds and phases [4]This work was financially supported by project "PLASTIC_TO_FUEL&MAT – Upcycling Waste Plastics into Fuel and Carbon Nanomaterials" (PTDC/EQU-EQU/31439/2017), Base Funding - UIDB/50020/2020 of the Associate Laboratory LSRE-LCM - funded by national funds through FCT/MCTES (PIDDAC), and CIMO (UIDB/00690/2020) through FEDER under Program PT2020. Fernanda F. Roman acknowledges the national funding by FCT, Foundation for Science and Technology, and FSE, European Social Fund, through the individual research grant SFRH/BD/143224/2019.info:eu-repo/semantics/publishedVersio

EFEITO DA APLICAÇÃO DE CINZAS DE BIOMASSA VEGETAL E NITROGÊNIO NA PRODUTIVIDADE DO CAPIM-TIFTON 85

Visando a elevação da fertilidade do solo e possíveis ganhos em produtividade, o uso da cinza da biomassa florestal é visto como um acessível meio de produção para a agricultura. Assim como a adubação nitrogenada é importante para determinar o ritmode crescimento e a qualidade das gramíneas forrageiras.O presente trabalho teve porobjetivoavaliar a composição química da forragem produzida pelo capim-tifton 85 submetido a diferentes doses de cinza juntamente com e sem nitrogênio aplicado em cobertura. A pesquisa foi realizada em uma propriedade rural na cidade de Xanxerê, SCno período de outubro de 2015 a janeiro de 2016. O delineamento experimental utilizado foi em blocos com parcelas subdivididas com 5 repetições. Os tratamentos foram: 1) Testemunha (sem adubo); 2) 4 t/ha de cinza; 3) 8 t/ha de cinza ; 4) 16 t/ha de cinza; e 5) 32 t/ha de cinza e em todas as parcelas foram subdivididas com aplicação de133 gramas por subparcela de ureia ou sem aplicação. Foram realizados dois cortes respeitados 30 dias entre cortes. Avaliou-se a matéria verde (MV) e a massa seca (MS), nas concentrações de N, P, K, Ca e Mg na planta inteira. No primeiro corte os teores de nitrogênio e potássio foram maiores nos tratamentos com aplicação de nitrogênio, enquanto no segundo corte, quando aplicamos o nitrogênio o teor de fosforo na forragem foi menor. Os demais elementos, não sofreram efeito das doses de de cinza e nem daa plicação ou não de nitrogênio.O capim-tifton 85 não apresentou resposta a dose de cinza sobre o teor dos nutrientes N, P, K, Ca e Mg na forragem, indiferente dos cortes

Selective denitrification of simulated oily wastewater by oxidation using Janus-structured carbon nanotubes

The intense industrial development has resulted in several consequences for human and environmental health, including the increased discharge of oily products in water bodies. Oily products are widely used in industry, often bearing an associated high cost. Finding alternatives to treat oily wastewater aiming at recovering oily and water phases is an approach allowing recovery of products of economic interest. In this work, Janus-like carbon nanotubes (CNTs) were synthesized by varying the feed time of acetonitrile and ethylene, respectively, as nitrogen/ carbon and carbon precursors in a chemical vapor deposition (CVD) approach. The CVD approach allowed the synthesis of completely undoped, completely doped and partially doped CNTs with a Janus structure. The CNTs were then tested as catalysts for the selective oxidation of 4-nitrophenol (4-NP) contained in a simulated oily wastewater (2,2,4-trimethylpentane/water (O/W) = 1:9, volume basis) by catalytic wet peroxide oxidation (CWPO). The CWPO experiments were conducted for 24 h, 80 ◦C, 2.5 g L-1 of catalyst, and the stoichiometric concentration of H2O2 (3.6 g L-1) for the degradation of 4-NP (1 g L-1). The same conditions were kept for experiments conducted under a biphasic system. The catalysts bearing a Janus-like structure were demonstrated to be more effective in CWPO experiments in aqueous-only and biphasic systems for the abatement of 4-NP.This work was financially supported by LA/P/0045/2020 (ALiCE), UIDB/50020/2020 and UIDP/50020/2020 (LSRE-LCM) funded by national funds through FCT/MCTES (PIDDAC); project “PLASTIC_TO_FUEL&MAT – Upcycling Waste Plastics into Fuel and Carbon Nanomaterials” (PTDC/EQU-EQU/31439/2017), CIMO (UIDB/00690/2020), and project “Healthy Waters” (NORTE-01–0145-FEDER-000069) through FEDER under Program PT2020. Fernanda F. Roman acknowledges the Foundation for Science and Technology (FCT) and the European Social Fund (FSE) for the individual research grant with reference SFRH/BD/143224/2019. Adriano S. Silva was supported by the doctoral Grant SFRH/BD/151346/2021 financed by FCT with funds from NORTE2020, under MIT Portugal Program. Jose L. Diaz De Tuesta acknowledges the financial support through the program of Atracción al Talento of Comunidad de Madrid (Spain) for the individual research grant 2020-T2/AMB-19836.info:eu-repo/semantics/publishedVersio

EFEITO DA APLICAÇÃO DE CINZAS DE BIOMASSA VEGETAL E NITROGÊNIO NA PRODUTIVIDADE DO CAPIM-TIFTON 85

Visando a elevação da fertilidade do solo e possíveis ganhos em produtividade, o uso da cinza da biomassa florestal é visto como um acessível meio de produção para a agricultura. Assim como a adubação nitrogenada é importante para determinar o ritmode crescimento e a qualidade das gramíneas forrageiras.O presente trabalho teve porobjetivoavaliar a composição química da forragem produzida pelo capim-tifton 85 submetido a diferentes doses de cinza juntamente com e sem nitrogênio aplicado em cobertura. A pesquisa foi realizada em uma propriedade rural na cidade de Xanxerê, SCno período de outubro de 2015 a janeiro de 2016. O delineamento experimental utilizado foi em blocos com parcelas subdivididas com 5 repetições. Os tratamentos foram: 1) Testemunha (sem adubo); 2) 4 t/ha de cinza; 3) 8 t/ha de cinza ; 4) 16 t/ha de cinza; e 5) 32 t/ha de cinza e em todas as parcelas foram subdivididas com aplicação de133 gramas por subparcela de ureia ou sem aplicação. Foram realizados dois cortes respeitados 30 dias entre cortes. Avaliou-se a matéria verde (MV) e a massa seca (MS), nas concentrações de N, P, K, Ca e Mg na planta inteira. No primeiro corte os teores de nitrogênio e potássio foram maiores nos tratamentos com aplicação de nitrogênio, enquanto no segundo corte, quando aplicamos o nitrogênio o teor de fosforo na forragem foi menor. Os demais elementos, não sofreram efeito das doses de de cinza e nem daa plicação ou não de nitrogênio.O capim-tifton 85 não apresentou resposta a dose de cinza sobre o teor dos nutrientes N, P, K, Ca e Mg na forragem, indiferente dos cortes

Amphiphilic carbon nanotubes for catalytic wet peroxide oxidation of 4-nitrophenol

Carbon nanotubes (CNTs) were synthesized via chemical vapor deposition (CVD) over an AlCoFeO4 catalyst by a sequential feed of ethylene (E, as carbon source) and acetonitrile (A, as nitrogen source). The resulting samples were noted E20 (hydrophobic), E10A10 (amphiphilic), and A20 (hydrophilic), the number referring to the feed time (minutes) of each precursor, as reported elsewhere1. These materials were tested in the catalytic wet peroxide oxidation (CWPO) of 4-nitrophenol (4-NP). The reaction was monitored by HPLC (to determine the concentration of 4-NP and respective intermediates), TOC analyzer, and UV-vis spectrophotometry (to quantify H2O2) (Figure 1). After 8 h of reaction, A20 led to the highest consumption of H2O2 (90%), followed by E10A10 (61%) and E20 (52%). On the other hand, the highest degradation of 4-NP was observed with the amphiphilic E10A10 material (98%) followed by E20 (95%), whereas A20 only led to a removal of 69%. Similar behavior was found when analyzing the formation of reaction intermediates (data not shown), i.e., while A20 resulted in the accumulation of 4-nitrocatechol (4-NTC) and hydroquinone (HQ) E10A10 and E20 led to the total conversion of formed 4-NTC and HQ. This resulted in a lower TOC removal for A20 (37%) than to E10A10 and E20 (53%). Therefore, the amphiphilic E10A10 material is a promising catalyst for the CWPO of 4-NP.This work was financially supported by project "PLASTIC_TO_FUEL&MAT – Upcycling Waste Plastics into Fuel and Carbon Nanomaterials" (PTDC/EQU-EQU/31439/2017), Base Funding - UIDB/50020/2020 of the Associate Laboratory LSRE-LCM - funded by national funds through FCT/MCTES (PIDDAC), and CIMO (UIDB/00690/2020) through FEDER under Program PT2020. Fernanda F. Roman acknowledges the funding by FCT, Foundation for Science and Technology, and FSE, European Social Fund, through the individual research grant SFRH/BD/143224/2019info:eu-repo/semantics/publishedVersio

Selective denitrification of a simulated oily wastewater using Janus-structured carbon nanotubes

Carbon nanotubes (CNTs) bearing a Janus-like structure were synthesized by chemical vapor deposition considering ethylene and acetonitrile as carbon and nitrogen sources. The developed materials were applied as catalyst in the oxidation of 4-nitrophenol (4-NP) dissolved in a biphasic medium (water/2,2,4-trimeylpentane) simulating a contaminated oily wastewater. The CNT prepared using both ethylene and acetonitrile precursors shows a Janus-structure, leading to the highest abatement of 4-NP as well as to the highest removal of TOC, proving to be an alternative towards the removal of lipophilic pollutants from oily effluents, allowing to reclaim the oily phase.This work was financially supported by project "PLASTIC_TO_FUEL&MAT – Upcycling Waste Plastics into Fuel and Carbon Nanomaterials" (PTDC/EQU-EQU/31439/2017), Base Funding - UIDB/50020/2020 of the Associate Laboratory LSRE-LCM - funded by national funds through FCT/MCTES (PIDDAC), and CIMO (UIDB/00690/2020) through FEDER under Program PT2020. F. F. Roman acknowledges the national funding by FCT, Foundation for Science and Technology, and FSE, European Social Fund, through the individual research grant SFRH/BD/143224/2019. A. Santos Silva was supported by the doctoral grant SFRH/BD/151346/2021 financed by FCT with funds from NORTE2020, under MIT Portugal Programinfo:eu-repo/semantics/publishedVersio